Board Thread:Pokémon Help/@comment-31398341-20171026040947/@comment-32358261-20171211215431

The main reason why fly shouldn’t be used in competitive is the fact that it makes you predictable for a turn. During that fly turn, opponent can switch to a resisted hit or simply protect. If the Pokémon has access to recovery then roost/synthesis/recover can be used.

Yes I know flynium z boosted fly can nuke things easy but the same power if not more can be found with other flying moves. After that first use, you can’t use it anymore and now you essentially have 3 moves unless you plan to use fly normally for whatever reason.

2 turn moves are uncommon in competitive play due to the predictability of it.